Devices are known from the prior art for analyzing the human running movement. Kinematic sensors, such as for instance inertial sensors (accelerometers, angular velocity sensors) and magnetometers, are used for this purpose. Devices are also known which can determine the transfer of forces between two bodies. Kinetic sensors such as for instance pressure sensors, force sensors and moment sensors are used here. A known method makes use of so-called force plates. Such plates provided with a plurality of force sensors are arranged on the surface. A test subject then steps onto the force plate, whereby the force plate is dynamically loaded. From the measured forces information is obtained about the interaction between the surface (force plate) and test subject. During running on a relatively hard surface the reaction forces of the surface and the acceleration of the foot do not generally equal zero simultaneously. When the foot is situated on the hard surface, the velocity of the foot will be substantially zero, while the reaction force will on the other hand differ from zero. When the foot is not situated on the surface, the reverse phenomenon occurs: the velocity of the foot will not equal zero while the measured reaction force is zero. That is, during running on a relatively hard surface no power is transferred from the foot to the surface, except possibly during the impact phase when the foot touches the surface during the transition from swing to standing phase.
There are however also circumstances which can be envisaged where power is transferred by means of a movement of a body, in particular of a human body. Power is thus produced for instance during all kinds of physical work, wherein objects are manipulated, or during sporting activity. At the moment there is no adequate device and method available which is able to measure the dynamic interaction between a first and a second body during relatively random movements, and in particular the power transfer from a first body to a second body. The ability to measure the interaction between two or more bodies during relatively random movements, for instance between the body of a sportsperson and a ball or between the body of the sportsperson and a preferably non-hard surface, provides useful information about the movement, about the forces and about the power transferred by the sportsperson to the ball or to the surface. Such information can be used to improve the performance of the sportsperson. Such information can also be of great value in ergonomics (the evaluation of physical load during work) and for disabled persons who use a prosthesis.
The present invention has for its object to provide a device and method for measuring the dynamic interaction between a first and a second body, particularly during relatively random movements.